The invention relates to an electromagnetically operated valve construction wherein permanent-magnet action is effective to latch, i.e., to retain, a selected open or closed condition of at least two valves, each of which is operative to control a different and independent flow of pressure fluid.
U.S. Pat. Nos. 3,443,585, 3,472,277, and 4,223,698 describe magnetically linked dual-valve systems wherein a single electromagnetic excitation is operative to drive each of two valve members, each of which serves its own separate pressure-fluid flow. In U.S. Pat. No. 3,443,585, a permanent magnet is the common middle leg of two separate solenoid-actuated magnetic circuits. Excitation of one solenoid opens both valves; excitation of the other solenoid closes both valves, and the permanent magnet holds the actuated condition of both valves. U.S. Pat. Nos. 3,472,277 and 4,223,698 each disclose an electromagnetic actuating system wherein a single solenoid coil actuates two magnetically linked valves to open condition, against the preloaded compliant action of springs to load valve members in the valve-closing direction. In all cases, construction of a final product is highly specialized and complex, leading to unduly expensive products.
Copending application Ser. No. 08/184,484, filed Jan. 19, 1994 describes a magnetically latched valve construction wherein electrical excitation of a single winding is required only for effecting a change of state of a single valve, from open to closed position and vice versa, depending upon the polarity of excitation of a single winding. Magnetic latching to retain one or the other of these states is achieved solely by a permanently magnetized portion of the magnetic circuitry; the disclosure of said copending application is hereby incorporated by reference.